Homocysteine: What Is It & What Levels Are Normal?

One of the main things I look at when someone comes into my clinic is something that often goes overlooked: homocysteine. Homocysteine1 is an amino acid that every single person has in their body. Even though it's important in certain amounts, when it's too high, it has been linked to autoimmune conditions, heart disease, and more.

Homocysteine is regulated during a biochemical process known as methylation. And if you haven't heard of it before, methylation is this big biochemical superhighway that makes sure we have a healthy immune system, brain, hormone system, and gut. The methylation process occurs about a billion times every second in your body, and if something is going wrong with the process of methylation, you're probably not feeling all that well. Methylation-gene mutations, such as MTHFR are closely associated with autoimmune-inflammation spectrum issues and keeping homocysteine at healthy levels. For example, I have a double mutation at the MTHFR C677t gene, which means my body is not good at managing homocysteine and I have to be extra diligent in supporting that genetic weakness. For a full rundown of the different methylation genes we look at in functional medicine, click here.

This is extremely important because your body needs SAMe and glutathione to put autoimmune reactions into remission. This happens through glutathione's role as the body's most powerful antioxidant and SAMe's ability to protect nerves and support neurotransmitters like serotonin and dopamine. Homocysteine can build up and continue to increase when methyl donors are inadequate. The optimal range for homocysteine in functional medicine is less than 7 μmol/L. When homocysteine is higher than this, you can see it play out in a multitude of seemingly unrelated health problems, including those related to autoimmunity and chronic inflammation.

When it comes to DNA and the protection it needs, it's extra important to keep methylation pathways and homocysteine levels healthy. When methylation isn't working correctly, it doesn't keep the good genes working and the bad genes in remission, and this can lead to autoimmune issues. High homocysteine levels are associated with incredibly common autoimmune diseases like Hashimoto's disease, rheumatoid arthritis, and psoriasis.

Heart attack and stroke can be brought on by autoimmune conditions—lupus and autoimmune thyroid disease, in particular—which we have seen are also affected by homocysteine levels. I've written many articles before about how cholesterol is not a good indicator of a healthy cardiovascular system. In fact, research shows that not only is it more important than cholesterol, but inflammatory markers like homocysteine are actually a better indicator of heart disease than other well-known risks like smoking and high blood pressure3.

Parkinson's disease, Alzheimer's, and multiple sclerosis are all neurological autoimmune spectrum diseases and can be linked to high homocysteine levels. As these levels rise, they can start to destroy the brain barrier to develop leaky brain syndrome. According to recent research, when homocysteine levels increase to 14 µmol/L or higher, the risk of Alzheimer's doubles6. This is especially important considering the growing rate of Alzheimer's; over 5.7 million Americans suffer from Alzheimer's today, and that number is expected to rise to 14 million by 2050. Keeping methylation pathways healthy by lowering homocysteine is a crucial step in protecting the brain from Alzheimer's and other forms of dementia.

Homocysteine can also affect the brain emotionally by increasing the risk of depression. Various studies have been completed that connect depressive thoughts to higher homocysteine levels because of its correlation to low serotonin levels. According to some, the high homocysteine levels present in women after giving birth is the contributing factor to postpartum depression7. This is also proven in a recent study involving a large group of men. The men with the highest third of homocysteine levels were two times more likely to struggle with depression than those in the lowest third.

If you want to start lowering your homocysteine levels right away, you can start by ensuring that you're consuming enough B vitamins. Activated forms of folate (methylfolate), B6 (oyridoxyl-5-phosphate), and B12 (methylcobalamine) are the best options to ensure healthy methyl pathways. Great foods to focus on to support healthy methylation pathways include green leafy vegetables, sulfur-rich vegetables like cabbage and broccoli sprouts, wild-caught fish, grass-fed beef, and organ meats like grass-fed liver3.